1. Field of the Invention
The present invention relates to a class of full-cyclized aromatic-polyimides and copolyimides prepared from alkyl substituted diamines and 4,4'-[2,2,2-trifluoro-1-(trifluoromethyl)ethylidene) bis (1,2-benzenedicarboxylic acid anhydride) (6FDA).
2. Prior Art
European Patent Applications 132,221, 141,781, and 181,837 and U.S. Nos. 4,629,685 and 4,629,777 disclose aromatic polyimides in which the diamines are substituted with alkyl groups but do not encompass use of the dianhydride, 6FDA. U.S. No. 4,629,777, col. 6, lines 23,51 discloses polyimides that are soluble in good polar, aprotic solvents.
U.S. No. 3,356,648 discloses the aromatic polyimide derived from 6FDA and 2,2-bis(4-aminophenyl) hexafluoropropane which is soluble in acetone.
U.S. No. 3,959,350 discloses aromatic polyimides derived from 6FDA and various unsubstituted diamines.
U.S. 3,546,175 discloses aromatic polyimides derived from pyromellitic dianhydride or 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 2,4-diaminoisopropyl benzene which are soluble in good aprotic solvents.
U.S. No. 4,145,522 discloses polyimides derived from amino-substituted 4-t-butylphthalic anhydride which have improved solubility characteristics.
U.S. No. 4,588,804 discloses soluble aromatic polyimides derived from 6FDA and various diamines.
U.S. No. 4,592,925 discloses soluble aromatic polyimides derived form 6FDA and 2,2-bis(2 or 3-diaminophenyl) hexafluoropropane.
NASA Technical Memorandum 89016, U.S. No. 4,595,548 and U.S. No. 4,603,061 disclose transparent aromatic polyimides derived from various dianhydrides including 6FDA and ether or thioether bridged multi-ring diamines.